The present invention pertains to lubricants and more particularly to ester oil-silicone based greases.
Many applications for lubricants require the lubricant to operate in an environment having high pressure and high shear conditions, a temperature variation from below freezing to above the boiling point of water, a high moisure content, and a close proximity to sea water. Examples of such environment are found in naval rapid firing guns. It is required that lubricants for these guns be effective from -54.degree. to +150.degree.C.
Existing lubricants have had objectionable failings with regards to one or more of these environmental conditions. For example, if a lubricant provided adequate resistance to wear due to high pressure, it provided poor resistance to moisture. This low moisture resistance characteristic of the lubricant quickly caused corrosion and inoperability under icing conditions. One lubricant was sufficiently fluid, icing-resistant, and low temperature operable, but lacked sufficient resistance to wear due to high pressure.
One attempt to improve the lubricants has entailed the addition of silicones. This addition does improve the viscometric properties and moisure resistance of the lubricant, but it also increases wear and may cause compatibility problems with other lubricant components at low temperatures. The addition of effective chemical high pressure antiwear additives and corrosion inhibitors has heretofore been unsuccessful because of compatibility difficulties or a tendency of the additive to hydrolyze or to promote emulsification of the lubricant with water.